The present disclosure relates to AC windings of electric machines, and particularly, to cooling systems integrated with AC windings of high frequency electrical machines, and further, to a method of manufacture for making the AC windings.
It is well known that the capacity and efficiency of electric machines, such as motors and generators, can be improved by providing appropriate cooling systems for dissipating heat generated during operation. A variety of cooling methods have evolved for minimizing the effects of generated heat.
Known cooling methods include application of a cooling medium, such as air or a fluid to the exterior or a portion thereof of an armature winding, such as within a closed or open chamber housing the armature winding, or through conduits, such as pressurized or non-pressurized conduits contacting the exterior of the armature winding. Such approaches are illustrated, for example, in U.S. Pat. No. 3,609,420 issued Sep. 28, 1971 to Inagaki et al.; U.S. Pat. No. 3,648,085 issued Mar. 7, 1972 to Fujii; U.S. Pat. No. 4,517,479 issued May 14, 1985 to Aleem et al.; and commonly owned U.S. Pat. No. 6,438,969 issued Aug. 27, 2002 to Laskaris et al.
Another approach to cooling the armature winding includes the method of providing the armature winding with hollow conductors through which a cooling medium flows for dissipation of heat. A representative patent describing the above method is U.S. Pat. No. 3,634,705 issued Jan. 11, 1972 to Fidei. Further, it is known to co-wind cooling tubes with armature winding turns.
The occurrence of AC losses in armature windings is also known to negatively affect capacity and efficiency of electric machines. In high frequency machines used for applications calling for high speed and/or high power density, such as machines operating at frequencies significantly higher than 60 Hz, the AC losses can dominate operation of the electric machine. Furthermore, the heat generation escalates such that known cooling techniques are not sufficient or practical. For example, the cooling method using hollow conductors becomes impractical, as the conductors in high frequency machines are typically numerous, thin, and not conducive to having an interior channel.
Accordingly, there is a need for an improved armature winding usable in high frequency electric machines for minimizing AC losses and for improving cooling techniques.
Furthermore, there is a need for a cost effective method of manufacture for the improved armature winding.